Sift 2 cups flour into a large bowl. In a separate bowl, whisk egg yolk and then mix in beer, butter and salt. Slowly stir the egg yolk mixture into the flour and mix well; set aside for about 40 minutes. Heat deep fryer to 350°F. In a small bowl, beat the egg white until stiff peaks form. Gently fold egg white into the batter. Dip each ring into the remaining 1 cup flour and then the batter; deep fry rings until golden coloured. Drain on paper towels or and serve hot. Serves 6.